NodeJS + MongoDB: Getting data from collection with findOne ()

I have a collection "companies" with several objects. Every object has "_id" parameter. I'm trying to get this parameter from db:

app.get('/companies/:id',function(req,res){
db.collection("companies",function(err,collection){
    console.log(req.params.id);
    collection.findOne({_id: req.params.id},function(err, doc) {
        if (doc){
            console.log(doc._id);
        } else {
            console.log('no data for this company');
        }
    });
});
});

So, I request companies/4fcfd7f246e1464d05000001 (4fcfd7f246e1464d05000001 is _id-parma of a object I need) and findOne returns nothing, that' why console.log('no data for this company'); executes.

I'm absolutely sure that I have an object with _id="4fcfd7f246e1464d05000001". What I'm doing wrong? Thanks!

However, I've just noticed that id is not a typical string field. That's what mViewer shows:

"_id": {
        "$oid": "4fcfd7f246e1464d05000001"
    },

Seems to be strange a bit...